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In the quest for efficient, cost-effective and commercially viable fuel cells, scientists at Cornell University’s Energy Materials Center have discovered a catalyst and catalyst-support combination that could make fuel cells more stable, conk-out free, inexpensive and more resistant to carbon monoxide poisoning. (Journal of the American Chemical Society, July 12, 2010.)

Hydrogen fuel cells offer an appealing alternative to gasoline-burning cars: They have the potential to power vehicles for long distances using hydrogen as fuel, mitigate carbon dioxide production and emit only water vapor.

However, fuel cells generally require very pure hydrogen to work. That means that conventional fuels must be stripped of carbon monoxide – a process that is too expensive to make fuel cells commercially viable.

The problem is that platinum and platinum/ruthenium alloys, which are often used as catalysts in PEM (proton exchange membrane) fuel cells, are expensive and easily rendered ineffective by exposure to even low levels of carbon monoxide.

To create a catalyst system that can tolerate more carbon monoxide, Abruña, DiSalvo and colleagues deposited platinum nanoparticles on a support material of titanium oxide with added tungsten to increase its electrical conductivity.

Their research shows that the new material works with fuel that contains as much as 2 percent carbon monoxide – a level that is about 2000 times that which typically poisons pure platinum. Also, the material is more stable and less expensive than pure platinum. With the new catalyst, said Abruña, “you can use much less-clean hydrogen, and that’s more cost-effective because hydrogen derived from petroleum has a very high content of carbon monoxide. You need to scrub off the carbon monoxide and it’s very expensive to do that.”

The researchers are now preparing to put the catalyst to the test in real fuel cells. “So far, indications are very good,” Abruña said.

In preliminary experiments comparing the new material’s performance with pure platinum, he added, the platinum cell was readily poisoned by carbon monoxide and conked out early. Said Abruña: “But ours was still running like a champ.”

The research was supported by the U.S. Department of Energy and by the Energy Materials Center at Cornell, an Energy Frontier Research Center funded by the Department of Energy.

The U.S. Department of Energy (DOE) National Renewable Energy Laboratory (NREL) first began evaluating hydrogen-fueled transit buses in 2000 as part of its extensive technology validation efforts. These evaluations are funded by DOE and the U.S. Department of Transportation’s Federal Transit Administration. Over the years, NREL has collected and analyzed data on nine early generation fuel cell buses operated by four transit agencies in the United States.

In 2007, one of the manufacturers replaced the early generation fuel cell power systems in five of the buses with newer systems that featured improvements based on lessons learned during prior operation. According to NREL’s evaluation, these current generation systems show significant improvements in durability and reliability.

“Reliability increased by 21% after the installation of the new fuel cell systems,” Eudy said.

One measure of reliability and durability for the transit industry is “miles between roadcalls.” A roadcall is the failure of an in-service bus that requires it to be replaced on route or causes a significant scheduling delay. NREL data show a substantial increase in fuel cell-related “miles between roadcalls” after the installation of the new fuel cell systems.

As of June 2010, two of the fuel cell systems have accumulated a record number of hours without requiring repair or replacement of single fuel cells or cell stacks—one bus accrued more than 7,000 hours, and another more than 6,000. And, the fuel cells continue to operate at rated power.

How does a fuel cell work?
A fuel cell uses the chemical energy of hydrogen to cleanly and efficiently produce electricity with water and heat as byproducts. To see this process in action, view the fuel cell animation.

Fuel cells are unique in terms of the variety of their potential applications; they can provide energy for systems as large as a utility power station and as small as a laptop computer. A single fuel cell produces approximately 1 volt or less—barely enough electricity for even the smallest applications. To increase the amount of electricity generated, individual fuel cells are combined in series to form a stack. Depending on the application, a fuel cell stack may contain only a few or as many as hundreds of individual cells layered together. This “scalability” makes fuel cells ideal for a wide variety of applications, from laptop computers (50-100 Watts) to homes (1-5 kW), vehicles (50-125 kW), and central power generation (1-200 MW or more).

Pretoria – The Department of Science and Technology has partnered with Anglo Platinum and Altergy Systems to establish a new company that will distribute its products and manufacture fuel cells for the sub-Saharan African market.

The department, through its Technology Innovation Agency (TIA); Anglo Platinum through its Platinum Group Metals Development Fund (PGMD Fund); and California-based Altergy have agreed to establish a fuel cell marketing, distribution and manufacturing entity, Clean Energy Incorporated, under a license arrangement.

Both the department through the TIA and PGMD Fund will invest in the transaction, and along with Altergy, will each receive an equity position in Clean Energy.

The equity allocation creates a “partnering model” that aligns all shareholder objectives in Clean Energy to be channeled for success.

Anglo Platinum head of marketing development and research, Anthea Bath said: “We are pleased that our partnership with government and other role players in the industry is bearing tangible results.

“We believe this will go a long way in ensuring that we further develop the PGM market and is a boost for local beneficiation.”

Science and Technology Minister, Naledi Pandor said the initiative is in line with her department’s goal of promoting South Africa as a source of world class, high technology transfer and infrastructure opportunities.

“Our department is part of the Economic Sector and Employment Cluster that has prioritised cross-cutting interventions to promote decent work,” she said.

The initial primary objectives of the new company will be to develop a market for the Altergy products by marketing and setting up a distribution network throughout the Sub-Saharan region.

Thereafter, following the successful development of the market, Clean Energy will look to establish a manufacturing and assembly plant in South Africa which will ultimately supply the Sub-Saharan and World Wide markets with high quality fuel cell products

Altergy will initially provide market development services during the initial market development stage and thereafter assembly line services once the manufacturing and assembly plant is commissioned.

Most fuel cells use platinum-group-metals (PGM) as a catalyst for the conversion of hydrogen into electricity.

With 75 percent of the world PGM reserves residing locally, South Africa has to be an active participant in the nascent “hydrogen economy”.

This will ensure that South Africa enjoys the economic returns on beneficiation processes and is able to promote the growth of the knowledge economy in line with the National Hydrogen and Fuel Cells Research, Development and Innovation Strategy (HySA).

In May 2007, Cabinet approved the department’s initiated Hydrogen and Fuel Cell Technologies Research, Development and Innovation Strategy, branded HySA.

HySA is a culmination of various national policies of the department in respect of research and development. The objectives of HySA are to achieve the aim of creating a Hydrogen Economy, as well as to enable South Africa to move towards a knowledge-based economy.

Most importantly, the objective is to enable South Africa to extract more value from beneficiation of its natural resources, in this case, the abundant PGM resources.

The ultimate goal of this national strategy is to supply 25 percent of the world catalyst demand by 2020. -BuaNews

Iranian researchers could improve fuel cell efficiency by synthesizing a combined structure of micro fiberssilver nanoparticle and its successful application in the oxygen reduction reaction.

“The combined structure of micro fibers–silver nanoparticle creates a better conductivity within the composite in comparison with silver nanoparticles due to its one-dimensional structure,” said Nafiseh Sharifi, one of the researchers from Sharif University of Technology, Fars News Agency reported.

“We succeeded in synthesizing a combined structure of micro fibers-silver nanoparticle from cellulose fibers of cotton through a new method. The simplicity of the method is one of its advantages over the current methods,” she added.

She first coated silver nanoparticles on cellulose fibers of cotton by inducing chemical reactions. Then she removed cellulose from the coating that contained nanoparticles through heat treatment. Cellulose fibers acted as a template and nanoparticles took the form of the cellulose tissues.

The fibers consisted of nanoparticle chains. These one-dimensional structures act as a conductor in addition to being catalyst for oxygen reduction process due to their high effective area and desirable conductivity of silver.

In the next stage, nanostructured silver fibers with various concentrations were used in a graphite composite electrode. The presence of a combined structure of micro-fibers–silver nanoparticle increased the density of the current and decreased the potential of the reducer. As a result, oxygen reduction processes were improved.

The method is expected to considerably improve the efficiency of fuel cells.

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